get one mcb off, take it with you to TLC branch (they have good selection of contactum gear) and compare the sizes.
looking at the picture RCD wont fit in there anyway as there is only one available space next to the incomer... rcd takes two.
maybe you can do with separate rcd on the tails before cu.
From what I've read here old Contactum are a bit crap but I've had no problems with the new (CP) range and thier re-branded BG boards have good reviews
As mentioned above TLC sell it and they have some of their older gear as well (rcbos at £30 each), I'd ring or pop in and ask them for a side by side comparison.......or ebay
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